How much power does an average recreational rider generate whenclimbing?

Art Harris wrote:

I'm not talking about TdF riders, or amateur racers, or even local
"animals."

How much power can a typical, reasonably fit recreational rider
produce on long climbs.

You don't need anything fancy to get a pretty fair estimate.

If you have a steep hill that keeps your speed well down in the single digit
range, saying that all of the work goes against gravity is a pretty good
approximation.

Then, to get average power in watts for a particular climb, calculate

Gross Weight in lbs * Elevation Gain in feet *
0.000377 (watt-hour/foot-pound) * 3600 (seconds/hour) / total time for the
climb, in seconds

Power lost to wind resistance goes up with the cube of speed, so on a hill
that drops you to 1/3 of your speed on level ground for the same effort,
say 21 MPH to 7 MPH, 1/27th, or less than 4% of power goes to the wind.
The steeper the climb, the better the result.

I don't have an estimate for the power lost to tires, but for road style
tires I assume that this is also fairly small.

By this calculation, I make around 190 watts on a climb of about an hour.
I'm 59. I ride recreationally, but don't "train" in any sense of the word.

-- Andy Heninger


For instance, you're doing a 60-mile ride,
cruising along at about 16-17 mph in rolling terrain, and then
encounter a 1-mile 8-percent grade? Obviously, you're going to work
harder on the climb. But how hard can you go on the climb without
blowing up? 150 Watts? 200 Watts? 250 Watts?

Any Power Tap users out there?

Art Harris

| But from a practical standpoint, I weigh 175 (too much for my 6' frame),
|
| not necessarily so.
|
| http://www.reuters.com/article/healt...66953420070316

If I didn't wear *all* of my fat just above the belt, I might agree with you. I know; supposedly a hereditary thing. Arms like toothpicks, legs with skin pretty much stretched across muscle, but a gut. It's just not fair! I could lose 10 pounds and be just fine.

In any event, all my weight loss & gain comes from the same area. The only other variable is water retention, which is largely dependent upon diet. Lots of salt, and what do you know, my feet swell (which I wouldn't notice except when putting on cycling shoes). Real rocket science there.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com





"jim beam" wrote in message t...
| Mike Jacoubowsky wrote:
| "Art Harris" wrote in message
| ...
| I'm not talking about TdF riders, or amateur racers, or even local
| "animals."
|
| How much power can a typical, reasonably fit recreational rider
| produce on long climbs. For instance, you're doing a 60-mile ride,
| cruising along at about 16-17 mph in rolling terrain, and then
| encounter a 1-mile 8-percent grade? Obviously, you're going to work
| harder on the climb. But how hard can you go on the climb without
| blowing up? 150 Watts? 200 Watts? 250 Watts?
|
| Any Power Tap users out there?
|
| Art Harris
|
| Art: The *huge* variable is rider weight. A lighter rider will have much
| lower power figures for the same rate of climb than a heavier rider. There
| are two standards for rating how well racers perform- watts/kilogram of
| weight, and VAM (meters climbed/hour).
|
| But from a practical standpoint, I weigh 175 (too much for my 6' frame),
|
| not necessarily so.
|
| http://www.reuters.com/article/healt...66953420070316
|
| 52
| years old, and can do a long climb (4+ miles) at about 325 watts and a heart
| rate between 164-170 (absolute redline at 177, so technically I'm way beyond
| the theoretical 80% for a sustained effort, but I think they're recognizing
| the flaws on that one, plus there may be differences that come into play for
| someone who's relatively fit but somewhat asthmatic).
|
| Here's the strange thing. As I've gotten older, I can sprint better (I tell
| my legs what to do, and they do it... just not for long!) but the steeper
| stuff is no longer my friend.
|
| One other thing. When you ask how hard you can go without blowing up, there
| are different ways of blowing up. There's the total blow up where you go
| from full throttle to maybe half-speed and never recover, vs blowing up,
| taking a breather and then getting back to it (essentially interval
| training).
|
| --Mike Jacoubowsky
| Chain Reaction Bicycles
| www.ChainReaction.com
| Redwood City & Los Altos, CA USA
|
|

On Aug 5, 10:22*pm, wrote:
Dear Art,

Here's another calculator that might suit your interest:
*http://bikecalculator.com/wattsUS.html

Enter weight, grade, and so forth, then put in the mph that you manage
before blowing up, and it predicts watts.

Let's say that your 16-17 mph in rolling terrain translates to 20 mph
on the flats (round numbers are fun). You've mentioned 190 lbs, try
tubulars on the drops (the RR for clinchers vs. tubulars may be a bit
outdated), ignore age because RBT posters only grow more powerful with
age--

Round 169 watts on the flats up to 170 watts.

Now stick 170 watts into the companion watts-to-mph that Kerry
mentioned
*http://bikecalculator.com/veloUS.html

It predicts 20.03 mph on the flats, 4.52 mph up an 8% grade.

Let's bump the power to 200 watts--5.30 mph up the 8% grade.

You could reverse things, using the mph that you can hold steadily up
the 8% grade, and get an idea of watts.

When you climb at such low speeds, wind drag doesn't change things
much--higher temperatures and elevations will have hardly any effect
on the speed, even with x.xx precision.

Changing from the drops to the hoods doesn't matter much, either. The
200 watt speed of 5.30 mph up the 8% grade drops to 5.28 mph if you
sit up and grap the tops.

Even small winds won't matter much--at 200 watts up the 8% grade, a 5
mph headwind that knocks 3 mph off the 21.3 mph flat speed will reduce
the 5.30 mph climbing speed only 0.17 mph.

Carl,

I hope you don't mind if I interject a bit here.

While I can see headwinds not mattering much @ 5mph, I must admit I
don't really ride that slow, ever. My gearing combined with my bad
knee just doesn't mesh with that speed, I'm more likely to crank
harder to keep cadence up. Anyway, since you're debunking so many of
the things I seem to notice when riding, I'm curious your take on a
headwind at say... 20MPH. Perceptive or not, here are a few things I
notice when riding:

a) getting into the drops from the hoods or tops makes going easier,
especially at 18+MPH, and even more so at 23-25MPH.
b) Riding a lighter bike requires much less effort. For example, my
dads mountain bike weights well over 35lbs., closer to 40 if I
recall. Mine weighs just over 25. His hubs tend to spin even more
freely than mine, regardless of his being a BST. Mine have many years
and miles of abuse on them and are in dire need of a rebuild, and his
are fairly new, which I believe explains this. His bike has rear
suspension, but I've got it dialed so tight it doesn't really move.
Still, I find riding his bike to be extremely tiring, like riding
through loose snow. He has trouble riding around the block on his
bike, just over 1 mile all paved with some hills. The first time I
got him to try mine we did almost 5 miles, more than half of which was
off-road, including the same 1 mile with hills that normally wears him
out. At the end of the ride on my bike his complaint wasn't being
worn out, but saddle soreness.
c) Headwinds slow me down and make me work harder.

It's not that I can't maintain the same speeds under these adverse
circumstances (heavier bike, headwind, riding upright) but that I wear
myself out a whole lot sooner. On my new bike (full geared, fairly
lightweight "racing" style bike my low-end speeds are right aroudn the
average speeds on my old heavy singlespeed commuter. My average
speeds are a good 25% faster, and I feel less cooked and sweaty at the
end of the commute.

Minor changes in grade don't do much--8.2% drops the 5.30 mph speed
down to 5.18, while 7.8% raises it to 5.43 mph.

Again, I don't tend to slow down a lot for hills, especially of that
grade, but they certainly take a lot more out of me. Isnt' that what
this is about?


Surprisingly, even weight doesn't have as much effect as our obsession
with grams leads us to believe. Add 7 pounds to the 22-lb default
bike, and the 5.30 mph on-the-drops 200-watt speed falls to 5.14 mph.
(In other words, you don't need to toss your water bottle.)

If you want to find Power Tap users, you can join the moderated
wattage group and browse a bit:
*http://groups.google.com/group/wattage

You may not even have to join--try clicking on "discussions" on the
link above, or try this link:
*http://groups.google.com/group/wattage/topics

Cheers,

Carl Fogel

On Aug 6, 12:01*am, "Mike Jacoubowsky" wrote:
| But from a practical standpoint, I weigh 175 (too much for my 6' frame),
|
| not necessarily so.
|
|http://www.reuters.com/article/healt...66953420070316

If I didn't wear *all* of my fat just above the belt, I might agree with you. I know; supposedly a hereditary thing. Arms like toothpicks, legs with skin pretty much stretched across muscle, but a gut. It's just not fair! *I could lose 10 pounds and be just fine.

In any event, all my weight loss & gain comes from the same area. The only other variable is water retention, which is largely dependent upon diet. Lots of salt, and what do you know, my feet swell (which I wouldn't notice except when putting on cycling shoes). Real rocket science there.

Heh. Skinny white guys with guts represent.

I'm currently at 190 lbs, I'm about 5'11" - for years I dreamed of
being able to weigh this much. when I was in college I was trying to
stay competitive on the varsity swimming team and was eating
everything in sight to try to keep up with the calories I was burning
in workouts. I never could get over 180 lbs. no matter how hard I
tried.

Now, I look just like you describe - little nothin' arms, legs like
tree trunks, but what the heck is going on around the waist area?

Unfortunately now that my metabolism has slowed some, I just can't
seem to find the time, and more importantly the discipline, to work
out enough to redistribute that newfound mass appropriately...

nate

On Aug 5, 12:00*pm, "Kerry Montgomery" wrote:
"Art Harris" wrote in message

...



I'm not talking about TdF riders, or amateur racers, or even local
"animals."

How much power can a typical, reasonably fit recreational rider
produce on long climbs. For instance, you're doing a 60-mile ride,
cruising along at about 16-17 mph in rolling terrain, and then
encounter a 1-mile 8-percent grade? Obviously, you're going to work
harder on the climb. But how hard can you go on the climb without
blowing up? 150 Watts? 200 Watts? 250 Watts?

Any Power Tap users out there?

Art Harris

Hi Art,
This calculator:http://bikecalculator.com/veloUS.html
lets you estimate the power required for a certain climb at a certain speed
and weight, so you can input different power values until the time comes out
to the actual value. For your example above, if you input 8% and 1 mile and
leave everything else at default values, it predicts that at 100W it would
take 18.5 minutes at an average speed of 3.25 mph to do the climb. At 250 W,
it'd take 7.7 minutes. Don't know how close its results are to a PowerTap -
that'd be a very interesting comparison for someone to do.
Kerry- Hide quoted text -

- Show quoted text -

Pretty interesting calculator. The Wabash trail in Springfield, IL
seem to have a tiny incline that is not really visible. I entered my
weight 290 pounds, 50 pound bicycle, clinchers, bar ends, head wind 0
miles 2 temp 75F, Elev 600 ft, Eff 95. Started with the 100 watts and
1% and -1% slope. Too fast descent and slow on the climb. Cut the
slope and both speeds too high. Cut the power to get the speeds
closer Finalized on at 66 watts and 0.3 and -0.3 slope and they
matched my speed.

On Aug 6, 10:53 am, N8N wrote:
On Aug 6, 12:01 am, "Mike Jacoubowsky" wrote:

| But from a practical standpoint, I weigh 175 (too much for my 6' frame),
|
| not necessarily so.
|
|http://www.reuters.com/article/healt...66953420070316

If I didn't wear *all* of my fat just above the belt, I might agree with you. I know; supposedly a hereditary thing. Arms like toothpicks, legs with skin pretty much stretched across muscle, but a gut. It's just not fair! I could lose 10 pounds and be just fine.

In any event, all my weight loss & gain comes from the same area. The only other variable is water retention, which is largely dependent upon diet. Lots of salt, and what do you know, my feet swell (which I wouldn't notice except when putting on cycling shoes). Real rocket science there.

Heh. Skinny white guys with guts represent.

I'm currently at 190 lbs, I'm about 5'11" - for years I dreamed of
being able to weigh this much. when I was in college I was trying to
stay competitive on the varsity swimming team and was eating
everything in sight to try to keep up with the calories I was burning
in workouts. I never could get over 180 lbs. no matter how hard I
tried.

Now, I look just like you describe - little nothin' arms, legs like
tree trunks, but what the heck is going on around the waist area?

Unfortunately now that my metabolism has slowed some, I just can't
seem to find the time, and more importantly the discipline, to work
out enough to redistribute that newfound mass appropriately...

nate

One more paragraph about body fat, Nat and we shall rename this
group as alt.fat.middle_age.bikers.whining (while trying hard to
catch one last glimpse of lost youth) ;-)

In article
,
N8N wrote:

On Aug 6, 12:01*am, "Mike Jacoubowsky" wrote:
| But from a practical standpoint, I weigh 175 (too much for my 6' frame),
|
| not necessarily so.
|
|http://www.reuters.com/article/healt...66953420070316

If I didn't wear *all* of my fat just above the belt, I might agree with you. I know; supposedly a hereditary thing. Arms like toothpicks, legs with skin pretty much stretched across muscle, but a gut. It's just not fair! *I could lose 10 pounds and be just fine.

In any event, all my weight loss & gain comes from the same area. The only other variable is water retention, which is largely dependent upon diet. Lots of salt, and what do you know, my feet swell (which I wouldn't notice except when putting on cycling shoes). Real rocket science there.

Heh. Skinny white guys with guts represent.

I'm currently at 190 lbs, I'm about 5'11" - for years I dreamed of
being able to weigh this much. when I was in college I was trying to
stay competitive on the varsity swimming team and was eating
everything in sight to try to keep up with the calories I was burning
in workouts. I never could get over 180 lbs. no matter how hard I
tried.

Now, I look just like you describe - little nothin' arms, legs like
tree trunks, but what the heck is going on around the waist area?

Unfortunately now that my metabolism has slowed some, I just can't
seem to find the time, and more importantly the discipline, to work
out enough to redistribute that newfound mass appropriately...

Pay attention to everything you eat.
The hard core keep a journal of what and how much.
Do not make judgments.
Do not attempt changes that make you feel deprived.

--
Michael Press

Kerry Montgomery wrote:
This calculator:http://bikecalculator.com/veloUS.html
lets you estimate the power required for a certain climb at a certain speed
and weight, so you can input different power values until the time comes out
to the actual value.

Hey, that's an interesting tool. According to it, I'm generating about
250 Watts.

Thanks, for the link.

Art harris

On Wed, 6 Aug 2008 06:51:55 -0700 (PDT), "
wrote:

On Aug 5, 10:22*pm, wrote:
Dear Art,

Here's another calculator that might suit your interest:
*http://bikecalculator.com/wattsUS.html

Enter weight, grade, and so forth, then put in the mph that you manage
before blowing up, and it predicts watts.

Let's say that your 16-17 mph in rolling terrain translates to 20 mph
on the flats (round numbers are fun). You've mentioned 190 lbs, try
tubulars on the drops (the RR for clinchers vs. tubulars may be a bit
outdated), ignore age because RBT posters only grow more powerful with
age--

Round 169 watts on the flats up to 170 watts.

Now stick 170 watts into the companion watts-to-mph that Kerry
mentioned
*http://bikecalculator.com/veloUS.html

It predicts 20.03 mph on the flats, 4.52 mph up an 8% grade.

Let's bump the power to 200 watts--5.30 mph up the 8% grade.

You could reverse things, using the mph that you can hold steadily up
the 8% grade, and get an idea of watts.

When you climb at such low speeds, wind drag doesn't change things
much--higher temperatures and elevations will have hardly any effect
on the speed, even with x.xx precision.

Changing from the drops to the hoods doesn't matter much, either. The
200 watt speed of 5.30 mph up the 8% grade drops to 5.28 mph if you
sit up and grap the tops.

Even small winds won't matter much--at 200 watts up the 8% grade, a 5
mph headwind that knocks 3 mph off the 21.3 mph flat speed will reduce
the 5.30 mph climbing speed only 0.17 mph.

Carl,

I hope you don't mind if I interject a bit here.

While I can see headwinds not mattering much @ 5mph, I must admit I
don't really ride that slow, ever. My gearing combined with my bad
knee just doesn't mesh with that speed, I'm more likely to crank
harder to keep cadence up. Anyway, since you're debunking so many of
the things I seem to notice when riding, I'm curious your take on a
headwind at say... 20MPH. Perceptive or not, here are a few things I
notice when riding:

a) getting into the drops from the hoods or tops makes going easier,
especially at 18+MPH, and even more so at 23-25MPH.

b) Riding a lighter bike requires much less effort. For example, my
dads mountain bike weights well over 35lbs., closer to 40 if I
recall. Mine weighs just over 25. His hubs tend to spin even more
freely than mine, regardless of his being a BST. Mine have many years
and miles of abuse on them and are in dire need of a rebuild, and his
are fairly new, which I believe explains this. His bike has rear
suspension, but I've got it dialed so tight it doesn't really move.
Still, I find riding his bike to be extremely tiring, like riding
through loose snow. He has trouble riding around the block on his
bike, just over 1 mile all paved with some hills. The first time I
got him to try mine we did almost 5 miles, more than half of which was
off-road, including the same 1 mile with hills that normally wears him
out. At the end of the ride on my bike his complaint wasn't being
worn out, but saddle soreness.

c) Headwinds slow me down and make me work harder.

It's not that I can't maintain the same speeds under these adverse
circumstances (heavier bike, headwind, riding upright) but that I wear
myself out a whole lot sooner. On my new bike (full geared, fairly
lightweight "racing" style bike my low-end speeds are right aroudn the
average speeds on my old heavy singlespeed commuter. My average
speeds are a good 25% faster, and I feel less cooked and sweaty at the
end of the commute.

Minor changes in grade don't do much--8.2% drops the 5.30 mph speed
down to 5.18, while 7.8% raises it to 5.43 mph.

Again, I don't tend to slow down a lot for hills, especially of that
grade, but they certainly take a lot more out of me. Isnt' that what
this is about?


Surprisingly, even weight doesn't have as much effect as our obsession
with grams leads us to believe. Add 7 pounds to the 22-lb default
bike, and the 5.30 mph on-the-drops 200-watt speed falls to 5.14 mph.
(In other words, you don't need to toss your water bottle.)

If you want to find Power Tap users, you can join the moderated
wattage group and browse a bit:
*http://groups.google.com/group/wattage

You may not even have to join--try clicking on "discussions" on the
link above, or try this link:
*http://groups.google.com/group/wattage/topics

Cheers,

Carl Fogel

Dear Dan,

Yikes!

Let's start with your last comment. Maybe you're overestimating the
steepness of the hills that you climb?

"Again, I don't tend to slow down a lot for hills, especially of that
grade, but they certainly take a lot more out of me."

That grade was 8%--Tour de France winners slow down an awful lot for
8% hills, even though it's only a rise of 8 feet in 100.

It's unlikely that a rider with a bad knee who talks about 18~25 mph
on the flats can climb 8% grades without tending to slow down an awful
lot.

Either you're slowing down much more than you think, your hills aren't
anywhere near 8%, or you're the next TDF winner.

I expect that you're posting in good faith, so please understand that
I'm just trying to explain how unlikely it is for _anyone_ to talk
about not slowing down a lot on 8% grades.

Have a look again at this side-by-side calculator:
http://bikecalculator.com/veloUS.html

The defaults and 200 watts will produce almost 20 mph for both sides.

Change one side to an 8% grade, and even 500 watts won't go 15 mph.

It's unlikely that you weigh 150 pounds and put out 500 watts for more
than a few seconds.

***

As for the mountain bike, even one in good repair is likely to be much
harder to ride because mountain bikes generally come with horrible
knobby tires (huge rolling resistance) and their flat bars force the
sit-up-and-beg position.

You can see this on the same side-by-side calculator:
http://bikecalculator.com/veloUS.html

Use the defaults and 200 watts on both sides, which should produce
19.67 mph. Now change the right side from hoods to drops, and the more
aerodynamic rider gains 1.63 mph and goes 21.30 mph. That 1.63 mph
doesn't sound like much, but it's 8.3% faster.

In other words, the calculator agrees with you--just ducking down on
the drops will make a fairly level paved ride much faster and easier.

The power needed to overcome wind drag rises with the cube of speed.
That is, if you double your speed, you need to devote 2^3 (2x2x2) as
much power to fighting wind drag. That's why aerodynamic improvements
pay off in road races and why Armstrong spent so much time in wind
tunnels.

(The _total_ power for twice the speed rises only ~6 times as much,
not 8 times as much, because the power spent on rolling resistance and
transmission losses doesn't need to rise anywhere near as fast as the
power spent on wind drag.)

You don't lose (or gain) as much speed due to head and tail winds as
the wind speed itself because part of the equation for wind drag and
power involves the distance.

When a headwind slows you down, you end up covering less distance in
the same time, so less power is needed, and you don't lose as much as
the total wind speed.

Similarly, when a tailwind speeds you up, you have to cover more
distance in the same time, so more power is needed, and you don't gain
as much as the total wind speed.

Again, the side-by-side calculator helps to illustrate this:
http://bikecalculator.com/veloUS.html

Use 200 watts with the defaults, and both sides go to 19.67 mph.

Change to 5 and -5 for the headwinds, and one side drops to 16.69, a
~3 mph loss, and the other side rises to only 22.90, a ~3 mph gain.

Neither side gains or loses the actual wind speed.

The slower you go, the less effect the wind will have, since wind drag
is tiny at low speeds--at 5 mph, you're putting your power into
deforming the tires, transmission losses, and (most likely) raising
your weight uphill.

***

Most of the speed gain that you notice between a mountain bike and a
touring-style drop-bar bike is likely to be due to better tires and
aerodynamics.

Consider the tires first:
http://bikecalculator.com/veloUS.html

Same old 200 watts with the defaults for both sides, same old 19.67
mph for both sides.

Now change from the default road-style clinchers to MTB tires.

Yikes! The speed drops from 19.67 mph to 17.85 mph, about 10% slower.
The tires deform as they roll, bulging outward as the rubber rolls
through the contact patch and then returning to the normal shape. The
more tire that you deform, the more power is lost--the "spring" of the
rubber never returns 100% of the power you put into deforming it.

Put a pair of high-pressure slick tires on a mountain bike, and the
speed rises. A few years ago, I rode a thousand miles in 4-mile daily
rides on a WalMart Fury RoadMaster with huge knobbies and then
switched to slicks--instant and sustained speed increase:
http://groups.google.com/group/rec.b...0e3ac9c2c9a35d

***

Now consider the weight of the mountain bike.

Even if one bike weighs 20 pounds and the other weighs 40, the
difference due to weight on the flats is tiny:
http://bikecalculator.com/veloUS.html

Use the defaults for both, plug in 200 watts, and change the bike
weights to 20 and 40--19.68 versus 19.53 mph. (For a rider who weighs
more than the default 150 pounds, the difference will be even less.)

The tiny difference in cruising speed on the flat is just the result
of the tiny increase in rolling resistance--the extra 20 pounds
deforms the tires a little more.

That's why a heavy single-speed can cruise at about the same speed on
the flat as a new multi-gear bike--weight means almost nothing on the
flat.

***

Uphill, an extra 20 pounds will slow things down more because you're
raising the weight, not rolling it on the flat.

Run the 20 and 40 pound bikes up an 8% grade at 200 watts, and one
goes 6.43 mph and the other goes only 5.80 mph, about 10% slower. When
you climb, more and more of your power goes into lifting raw weight
rather than overcoming wind drag.

But the effect of weight uphill is much less than our gram-counting
culture leads us to imagine. It's the _total_ weight that matters.
When you switch to a 40-lb bike from a 20-lb bike, you don't double
the weight that you have to pedal up the hill. You still weigh 150
pounds (using the default rider in the calculator), so you're going
from 150+20 to 150+40, which is from 170 to 190 pounds, a bit less
than a 12% increase in total weight, not a 100% increase.

You're probably not climbing 8% grades of any significant length on a
single-speed. In the early Tour de France, most of the single-speed
riders got off and walked for miles up such grades, pushing their
bicycles and cursing the organizers.

The 1910 TDF winner pushing up the Galibier:
http://magliarosa.files.wordpress.co.../08/lapize.jpg

Three 1920 TDF single-speed riders pushing up the Tourmalet:
http://i35.tinypic.com/fwq1hg.jpg

A 1934 TDF single-speed rider, pushing up the Izoard:
http://www.worldcycling.com/graphics...02/PSTP304.jpg

***

Anyway, you might look into the actual grade of the hills that you
ride and see if they're really 8%.

For fun, you can make an inclinometer with some cheap plastic pipe and
a right-angle ruler-level combination:

"Intrigued, I cobbled together an inclinometer, having read Jobst
Brandt's comments on grade percentages. Instead of an effete
Euro-style meter-bar, I used a five-foot piece of heavy-wall
straight plastic plumbing pipe, carving a chunk out 50 inches from the
end and dropping an ordinary carpenter's square through a slit in the
lower half of the pipe. The built-in level and the pipe cradling
the square, along with the adjusting screw to lock the ruler, made it
more convenient for a clumsy oaf to use and the extra ten inches make
it more accurate than a meter stick.
__
| |
| |--50"-------------------------------
______ | |______________________________________
| \____|__| |
| level visible inside pipe |
|_________________________________________________ ____|
| | /
| | 3" /
|__| /
\___touch road_____________________/


On an 8% grade, four inches of ruler would stick out below the pipe
when the bubble inside the pipe showed level.

A longer pipe will give even more accuracy.

Cheers,

Carl Fogel

On Aug 6, 4:14 pm, wrote:
Dear Dan,

Yikes!

Let's start with your last comment. Maybe you're overestimating the
steepness of the hills that you climb?

I must be overestimating the steepness of the hills I climb. What I
meant to say is that I rarely go under 10 MPH – I find my cadence gets
too slow and my bad knee bothers me. I am more likely to stand and
hammer to keep my cadence up. Since I really don’t know how to
estimate the grade of a hill, I’ll just assume I’m dead wrong on the
8% thing.


"Again, I don't tend to slow down a lot for hills, especially of that
grade, but they certainly take a lot more out of me."

That grade was 8%--Tour de France winners slow down an awful lot for
8% hills, even though it's only a rise of 8 feet in 100.

It's unlikely that a rider with a bad knee who talks about 18~25 mph
on the flats can climb 8% grades without tending to slow down an awful
lot.

There’s no doubt I slow down an awful lot – to me from 20+MPH to 10ish
MPH is an awful lot. What I meant to say is I don’t slow to 5MPH –
that would put my cadence far too low for comfort.


Either you're slowing down much more than you think, your hills aren't
anywhere near 8%, or you're the next TDF winner.

I’ll go for option B.


I expect that you're posting in good faith, so please understand that
I'm just trying to explain how unlikely it is for _anyone_ to talk
about not slowing down a lot on 8% grades.

Again, a lot is relative. I consider dropping to 10ishMPH from my
18-25 to be quite a bit. Still, I’m thinking I’m just off on the
grade estimate. Where I ride there are no grade signs, so I don’t
have much to judge by.


Have a look again at this side-by-side calculator:
http://bikecalculator.com/veloUS.html

The defaults and 200 watts will produce almost 20 mph for both sides.

Change one side to an 8% grade, and even 500 watts won't go 15 mph.

It's unlikely that you weigh 150 pounds and put out 500 watts for more
than a few seconds.

175ish, and have no idea the wattage I put out. I have strong legs,
but I’m willing to bet they’re not 500 watts of strong.


As for the mountain bike, even one in good repair is likely to be much
harder to ride because mountain bikes generally come with horrible
knobby tires (huge rolling resistance) and their flat bars force the
sit-up-and-beg position.

My point is that both bikes in question in the analogy referring to my
father are mountain bikes. The tires and sitting position are very
similar. One is a BST that weighs half a ton, and the other is a high-
end bike that is fairly light. I don’t think rolling resistance is
very different since his wheels will at least match if not outspin
mine in the upside-down wheel spinning test. There’s likely some
effort lost in the bottom bracket and derailers, but I doubt it’s a
whole lot. The difference in effort required to move each bike,
however, is a whole lot.


You can see this on the same side-by-side calculator:
http://bikecalculator.com/veloUS.html

Use the defaults and 200 watts on both sides, which should produce
19.67 mph. Now change the right side from hoods to drops, and the more
aerodynamic rider gains 1.63 mph and goes 21.30 mph. That 1.63 mph
doesn't sound like much, but it's 8.3% faster.

In other words, the calculator agrees with you--just ducking down on
the drops will make a fairly level paved ride much faster and easier.

The power needed to overcome wind drag rises with the cube of speed.
That is, if you double your speed, you need to devote 2^3 (2x2x2) as
much power to fighting wind drag. That's why aerodynamic improvements
pay off in road races and why Armstrong spent so much time in wind
tunnels.

(The _total_ power for twice the speed rises only ~6 times as much,
not 8 times as much, because the power spent on rolling resistance and
transmission losses doesn't need to rise anywhere near as fast as the
power spent on wind drag.)

You don't lose (or gain) as much speed due to head and tail winds as
the wind speed itself because part of the equation for wind drag and
power involves the distance.

When a headwind slows you down, you end up covering less distance in
the same time, so less power is needed, and you don't lose as much as
the total wind speed.

Similarly, when a tailwind speeds you up, you have to cover more
distance in the same time, so more power is needed, and you don't gain
as much as the total wind speed.

Again, the side-by-side calculator helps to illustrate this:
http://bikecalculator.com/veloUS.html

Use 200 watts with the defaults, and both sides go to 19.67 mph.

Change to 5 and -5 for the headwinds, and one side drops to 16.69, a
~3 mph loss, and the other side rises to only 22.90, a ~3 mph gain.

Neither side gains or loses the actual wind speed.

The slower you go, the less effect the wind will have, since wind drag
is tiny at low speeds--at 5 mph, you're putting your power into
deforming the tires, transmission losses, and (most likely) raising
your weight uphill.

***

Most of the speed gain that you notice between a mountain bike and a
touring-style drop-bar bike is likely to be due to better tires and
aerodynamics.

Again, I never compared road bikes to mountain bikes. The analogy I
used regarding my dad involves 2 mountain bikes, his and mine. Both
run similar tires and invoke similar riding position.


Consider the tires first:
http://bikecalculator.com/veloUS.html

Same old 200 watts with the defaults for both sides, same old 19.67
mph for both sides.

Now change from the default road-style clinchers to MTB tires.

Yikes! The speed drops from 19.67 mph to 17.85 mph, about 10% slower.
The tires deform as they roll, bulging outward as the rubber rolls
through the contact patch and then returning to the normal shape. The
more tire that you deform, the more power is lost--the "spring" of the
rubber never returns 100% of the power you put into deforming it.

Put a pair of high-pressure slick tires on a mountain bike, and the
speed rises. A few years ago, I rode a thousand miles in 4-mile daily
rides on a WalMart Fury RoadMaster with huge knobbies and then
switched to slicks--instant and sustained speed increase:
http://groups.google.com/group/rec.b...0e3ac9c2c9a35d

***

Now consider the weight of the mountain bike.

Even if one bike weighs 20 pounds and the other weighs 40, the
difference due to weight on the flats is tiny:
http://bikecalculator.com/veloUS.html

Use the defaults for both, plug in 200 watts, and change the bike
weights to 20 and 40--19.68 versus 19.53 mph. (For a rider who weighs
more than the default 150 pounds, the difference will be even less.)

The tiny difference in cruising speed on the flat is just the result
of the tiny increase in rolling resistance--the extra 20 pounds
deforms the tires a little more.

That's why a heavy single-speed can cruise at about the same speed on
the flat as a new multi-gear bike--weight means almost nothing on the
flat.

***

Uphill, an extra 20 pounds will slow things down more because you're
raising the weight, not rolling it on the flat.

Run the 20 and 40 pound bikes up an 8% grade at 200 watts, and one
goes 6.43 mph and the other goes only 5.80 mph, about 10% slower. When
you climb, more and more of your power goes into lifting raw weight
rather than overcoming wind drag.

While I don’t disagree with the speed difference at a given wattage, I
do wonder if we’re downplaying the effect this has on the endurance of
the cyclist. I’m not suggesting that 1/3lb will shave notable time
off of my commute, but it does seem to me that a bike that’s a few lbs
lighter requires less effort to get around, especially during
acceleration and going up hills.


But the effect of weight uphill is much less than our gram-counting
culture leads us to imagine. It's the _total_ weight that matters.
When you switch to a 40-lb bike from a 20-lb bike, you don't double
the weight that you have to pedal up the hill. You still weigh 150
pounds (using the default rider in the calculator), so you're going
from 150+20 to 150+40, which is from 170 to 190 pounds, a bit less
than a 12% increase in total weight, not a 100% increase.

You're probably not climbing 8% grades of any significant length on a
single-speed. In the early Tour de France, most of the single-speed
riders got off and walked for miles up such grades, pushing their
bicycles and cursing the organizers.

The 1910 TDF winner pushing up the Galibier:
http://magliarosa.files.wordpress.co.../08/lapize.jpg

Three 1920 TDF single-speed riders pushing up the Tourmalet:
http://i35.tinypic.com/fwq1hg.jpg

A 1934 TDF single-speed rider, pushing up the Izoard:
http://www.worldcycling.com/graphics...02/PSTP304.jpg

***

Anyway, you might look into the actual grade of the hills that you
ride and see if they're really 8%.

I think I’ll do this at some point, if nothing else to satisfy my
curiousity. I do wish we had signs around here like they have in some
other areas telling us these things.


For fun, you can make an inclinometer with some cheap plastic pipe and
a right-angle ruler-level combination:

"Intrigued, I cobbled together an inclinometer, having read Jobst
Brandt's comments on grade percentages. Instead of an effete
Euro-style meter-bar, I used a five-foot piece of heavy-wall
straight plastic plumbing pipe, carving a chunk out 50 inches from the
end and dropping an ordinary carpenter's square through a slit in the
lower half of the pipe. The built-in level and the pipe cradling
the square, along with the adjusting screw to lock the ruler, made it
more convenient for a clumsy oaf to use and the extra ten inches make
it more accurate than a meter stick.
__
| |
| |--50"-------------------------------
______ | |______________________________________
| \____|__| |
| level visible inside pipe |
|_________________________________________________ ____|
| | /
| | 3" /
|__| /
\___touch road_____________________/

On an 8% grade, four inches of ruler would stick out below the pipe
when the bubble inside the pipe showed level.

A longer pipe will give even more accuracy.

I may have to give this a whirl. Thanks for taking the time to reply.